The Ontario Building Code | Construction of Exposing Building Face
3.2.3.7. Construction of Exposing building Face
(1) Except as provided by Sentences (3) to (6) and Articles 3.2.3.10. and 3.2.3.11, the fire-resistance rating, construction and cladding for exposing building faces of buildings or fire compartmentsshall comply with Table 3.2.3.7.
(2) Reserved
(3) Except as provided by Sentences (4) to (6), cladding for buildings or fire compartmentswhere the maximum permitted area of unprotected openingsis more than 10% of the exposing building face need not be noncombustible where the wall assembly complies with the requirements of Sentences 3.1.5.5.(1), (3) and (4) when tested in conformance with CAN/ULC-S134, "Fire Test of Exterior Wall Assemblies".
(4) Except as provided by Sentence (6), cladding for buildings or fire compartments where the maximum permitted area of unprotected openings is more than 10% but not more than 25% of the exposing building face need not be noncombustible where the wall assembly complies with Article 3.1.5.5.
(5) Except as provided by Sentence (6), cladding for buildings or fire compartments where the maximum permitted area of unprotected openings is more than 25% but not more than 50% of the exposing building face need not be noncombustible where,
(a) the limiting distance is greater than 5 m,
(b) the buildingor fire compartment and all combustible attic or roof spaces are sprinklered,
(c) the cladding,
(i) conforms to Subsection 9.27.6., 9.27.7., 9.27.8., 9.27.9. or 9.27.10.,
(ii) is installed without furring members, or on furring not more than 25 mm thick, over gypsum sheathing at least 12.7 mm thick or over masonry, and
(iii) after conditioning in conformance with ASTM D2898, "Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing", has a flame-spread rating not greater than 25 on the exterior face when tested in accordance with Sentence 3.1.12.1.(1),
(d) the cladding,
(i) conforms to Subsection 9.27.12.,
(ii) is installed with or without furring members over gypsum sheathing at least 12.7 mm thick or over masonry,
(iii) has a flame-spread rating not greater than 25 when tested in accordance with Sentence 3.1.12.1.(2), and
(iv) does not exceed 2 mm in thickness exclusive of fasteners, joints and local reinforcements, or
(e) the wall assembly complies with Article 3.1.5.5.
(6) Subject to Sentence (7), cladding for buildings within the scope of Article 3.2.2.43A. or 3.2.2.50A. that exceed 4 storeysin building height or for fire compartments in such buildings where the maximum permitted area of unprotected openings is more than 10% of the exposing building face need not be noncombustible where the wall assembly complies with the requirements of Sentences 3.1.5.5.(3) and (4) when tested in accordance with CAN/ULC-S134, "Fire Test of Exterior Wall Assemblies".
(7) A wall assembly described in Sentence (6) that includes combustiblecladding of fire-retardant treated wood shall be tested for fire exposure after the cladding has been conditioned in conformance with ASTM D2898, "Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing".
(8) The construction requirements for the exposing building facethat are listed in Table 3.2.3.7. shall be satisfied before the area of unprotected openings may be increased as permitted by Sentence 3.2.3.12.(1).
Table 3.2.3.7.
Minimum Construction Requirements for Exposing Building Faces
Forming Part of Sentences 3.2.3.7.(1) and (8)
| Item | Column 1 Occupancy Classification of Building or Fire Compartment | Column 2 Maximum Area of Unprotected Openings Permitted, % of Exposing Building Face Area | Column 3 Minimum Required Fire-Resistance Rating | Column 4 Type of Construction Required | Column 5 Type of Cladding Required |
| 1. | Group A, B, C, D, or Group F, Division 3 | 0 to 10 | 1 h | Noncombustible | Noncombustible |
| > 10 to 25 | 1 h | Combustible or Noncombustible | Noncombustible | ||
| > 25 to 50 | 45 min | Combustible or Noncombustible | Noncombustible | ||
| > 50 to < 100 | 45 min | Combustible or Noncombustible | Combustible or Noncombustible (1) | ||
| 2. | Group E, or Group F, Division 1 or 2 | 0 to 10 | 2 h | Noncombustible | Noncombustible |
| > 10 to 25 | 2 h | Combustible or Noncombustible | Noncombustible | ||
| > 25 to 50 | 1 h | Combustible or Noncombustible | Noncombustible | ||
| > 50 to < 100 | 1 h | Combustible or Noncombustible | Combustible or Noncombustible (1) |
Notes to Table 3.2.3.7.:
(1) Cladding for buildings over 4 storeysin building height within the scope of Article 3.2.2.43A. or 3.2.2.50A. or for fire compartmentsin such buildings is required to be noncombustible.